Not being a wheel builder (or even remotely knowledgable), I'm curious as to if one could resell or reuse old spokes?

I just dismantled an old wheel and was wondering if it was safe to reuse them on a new wheel?

I asked a similar question (here and IRL/in real life) and was told
- if the spokes were not breaking, then it is worth a try, not an ideal thing but not a terrible idea
- it is best to sort the spokes into leading and trailing and use them in the same manner

I subsequently built a wheel re-using old spokes (that I forgot to sort) and it has been fine.

Then again, most spokes are not so expensive so there isn't a great reason to do this.

I flip bikes on CL and have made "serviceable" wheels out of various parts of junk wheels. A good hub from this & a good rim from that and have used old spokes. I'm retired and have more time than money, BTW-

Whenever I junk a wheel, I strip the spokes IF they are stainless, a length I'm short on and look OK.
I wouldn't think about buying or selling used spokes or using non stainless.

I rebuild wheels with used spokes all the time. However, these are on wheels that I originally built, so:
1. I know that the spokes are good quality
2. I know that the wheel was built to a high standard, correctly tensioned and well cared for
3. I sort the spokes into "inner" and "outer" sets when disassembling the wheel, so they go back in the same orientation

All of these might not be true on a random set of used spokes.

When I worked in a shop, we would cut out old spokes with cutters and dispose of them. It wasn't worth the time to carefully disassemble the wheel to save the old ones.

Maybe I'll hang on to them as practice wheel building spokes.

They look to be of good quality.

Wheelsmith double butted anyway

Hang on to them. When you use them again, look carefully at the J-bend. Half of them will be slightly stretched out, half of them will be bent a little more acutely. The "less bent" ones should be laced with the bend on the inside of the flange, the "more bent" ones go on the outside.

Enjoy yourself. Wheelbuilding is fun, but it can also be a lifetime addiction.